On Fri, Dec 4, 2020 at 2:15 AM Martin Cerveny <m.cerveny@xxxxxxxxxxxx> wrote:
>
> VideoEngine (cedrus) needs assign dedicated SRAM for decoding.
> SRAM_C1 is usually used for Allwinner platforms.
> Allwinner V3s scale down chip has not SRAM_C1 but only small SRAM_C (44kB).
>
> Result of additional testing:
>
> SRAM_C is mapped in two regions 0x0000_4000 (primary location,
> by Datasheet) (size is 0xb000, probably exact size is 0xb0c0
> and it is mapped to 4k boundary (to 0x0000_ffff))
> and to 0x01d0_4000 (traditional SRAM_C1 region from 0x01d0_0000).
>
> Rest of 0x01d0_0000 are discontinuously filled with R/W register sets
> (probably some internals registers from VE) that I thought to be SRAM too.
>
> Programming register SRAM_CTRL_REG0 (0x01c00_0000) with value 0x7fff_ffff
> switch out whole region 0x01d0_0000-0x01df_ffff and 0x0000_4000-0x0000_ffff
> (dedicate access to VE).
>
> VE/cedrus code use this SRAM region indirectly
> (VE_AVC_SRAM_PORT_OFFSET/VE_AVC_SRAM_PORT_DATA...)
> and it is not influenced by "real" SRAM mapping or size
> so it is working even without this patch.
>
> Signed-off-by: Martin Cerveny <m.cerveny@xxxxxxxxxxxx>
> ---
> arch/arm/boot/dts/sun8i-v3s.dtsi | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/boot/dts/sun8i-v3s.dtsi b/arch/arm/boot/dts/sun8i-v3s.dtsi
> index e8f304125e2d..bc4b4a0200cb 100644
> --- a/arch/arm/boot/dts/sun8i-v3s.dtsi
> +++ b/arch/arm/boot/dts/sun8i-v3s.dtsi
> @@ -162,17 +162,17 @@ syscon: system-control@1c00000 {
> #size-cells = <1>;
> ranges;
>
> - sram_c: sram@1d00000 {
> + sram_c: sram@4000 {
> compatible = "mmio-sram";
> - reg = <0x01d00000 0x80000>;
> + reg = <0x4000 0xb000>;
> #address-cells = <1>;
> #size-cells = <1>;
> - ranges = <0 0x01d00000 0x80000>;
> + ranges = <0 0x4000 0xb000>;
>
> ve_sram: sram-section@0 {
> compatible = "allwinner,sun8i-v3s-sram-c1",
Using C1 in the compatible string is confusing at this point, as the
name is never mentioned in the manual.
Please change it to sram-ve instead. Please also update the binding.
Since the DT patches this depends on haven't been merged yet, please
just do another version of the remaining patches with the changes
included.
ChenYu
> "allwinner,sun4i-a10-sram-c1";
> - reg = <0x000000 0x80000>;
> + reg = <0x0 0xb000>;
> };
> };
> };
> --
> 2.25.1
>
